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North Carolina Counties with 8-Hour Ozone Violations 2007-2009

In March 2008, the US EPA promulgated a revision of the ozone standard with a lower nonattainment threshold. We have colored the Design Value map in a novel way so that it can be compared easily to past years with the previous standard and to future years with the new standard.

Only one county, Mecklenburg, had a 3-year average of the annual 4th high value for each year equaling 0.085 ppm level or higher (violation of the 8-hour standard that was in effect from 1997 through 2007). The average for Mecklenburg County was 0.086 ppm. We present the remaining details in three tables. Table 1 refers to the ozone standard that was effective from 1997 through 2007. Table 2 and Table 3 refer to the ozone standard that was effective beginning in 2008.

Table 1. The following table shows 29 monitored counties that are attaining the 0.085 ppm standard that was in effect from 1997 through 2007. The first column lists the county; the second lists the average value for that county. On the 2007-2009 Design Value Map, these counties are colored orange and green, with orange signifying counties that would not attain the 2008 8-hour standard.

County

Average value

Alexander

0.073 ppm

Avery

0.067 ppm

Buncombe

0.069 ppm

Caldwell

0.071 ppm

Caswell

0.076 ppm

Chatham

0.069 ppm

Cumberland

0.074 ppm

Davie

0.078 ppm

Durham

0.074 ppm

Edgecombe

0.073 ppm

Forsyth

0.077 ppm

Franklin

0.074 ppm

Graham

0.075 ppm

Granville

0.077 ppm

Guilford

0.079 ppm

Haywood

0.074 ppm

Johnston

0.073 ppm

Lenoir

0.071 ppm

Lincoln

0.076 ppm

Martin

0.071 ppm

New Hanover

0.065 ppm

Person

0.074 ppm

Pitt

0.074 ppm

Rockingham

0.078 ppm

Rowan

0.084 ppm

Swain

0.064 ppm

Union

0.076 ppm

Wake

0.076 ppm

Yancey

0.074 ppm

Table 2. The following table shows 11 counties with a 3-year average of the annual 4th high value for each year equaling 0.076 ppm level or higher (violation of the 8-hour standard established in 2008). The first column lists the county; the second lists the average value for that county. On the 2007-2009 Design Value Map, these counties are colored red and orange, with red signifying counties that violated the 1997 8-hour standard and orange signifying counties attaining the 1997 8-hour standard.

County

Average Value

Caswell

0.076 ppm

Davie

0.078 ppm

Forsyth

0.077 ppm

Granville

0.077 ppm

Guilford

0.079 ppm

Lincoln

0.076 ppm

Mecklenburg

0.086 ppm

Rockingham

0.078 ppm

Rowan

0.084 ppm

Union

0.076 ppm

Wake

0.076 ppm

Table 3. The following table shows 19 monitored counties that are attaining the 0.076 ppm standard that was established in 2008. The first column lists the county; the second lists the average value for that county. On the 2007-2009 Design Value Map, these counties are colored green.